Yorta's Mother

Yorta, the antagonist in The Cage of Serimet, "is attended by two homonculi and a 7' stone woman, whom he addresses as 'Mother', which most often stands watch on the terrace [of Yorta's palace]. Mother wields a great bow of ivory and jet, which strikes as a small ballista."

Yorta's Mother is likely a golem of some sort. (A stone golem is CR 10 in 5th Edition.)